For a microwave unidirectional waveguide comprising of gyromagnetic photonic crystals (GMPCs),a discussion was made with emphasizing on the contributions of two factors, the lattice constant and the distance between metal confinement and GMPC,to the one way waveguide’s working characteristics.The study shows that the lattice constant has an evident effect on the unidirectional waveguide’s working frequency, while the distance between GMPC and metal confinement influences the waveguide’s modes of propagation.Suitable distance between GMPC and metal confinement leads the waveguide to presenting a better one way transmission property and less loss.A microwave unidirectional waveguide has been fabricated with yttrium iron garnet ferrite rods, and the measured unidirectional propagating regime (11.8~13.2 GHz) of this waveguide matches well with the simulated results.It is also demonstrated that the one way propagating characteristic will not be affected by defects along the waveguide passage.